Gastric constriction device

ABSTRACT

A gastric constriction device ( 160 ) comprises a sheet ( 131 ) extending over part of the wall of the stomach ( 24 ). Five bands ( 151 ) extend around the stomach ( 24 ) to fix the sheet ( 131 ) in position relative to the stomach ( 24 ). The lower two bands ( 151 ) extend from the first side ( 152 ) of the sheet ( 131 ) around the stomach ( 24 ) only partially towards the second side ( 153 ). These lower two bands ( 151 ) are not fixed to the second side ( 153 ). This arrangement results in an unconstricted portion of the stomach ( 161 ). In this manner, the device ( 160 ) restricts expansion of the majority of the stomach wall while facilitating expansion of this unconstricted portion ( 161 ). The unconstricted portion ( 161 ) is therefore free to expand or bulge outwardly upon ingestion. This expansion may trigger the feeling of satiation due to the presence of the vagal nerves in this portion ( 161 ) of the stomach ( 24 ).

This application claims the benefit of U.S. Provisional Application No.60/514,212, filed Oct. 23, 2003, the content of which is herebyincorporated by reference.

INTRODUCTION

This invention relates generally to a gastric constriction device, andmore specifically to gastric implants that can be used to treat obesepatients. In particular the invention relates to mechanical systems fortreating morbid obesity, especially to devices that interfacemechanically with a patient's digestive system in order to restrict foodintake.

BACKGROUND

Obesity is a major public health challenge and financial burden for mostindustrialised countries. In the United States, the healthcare costs fortreating obesity reached more than $238 billion in 1999. The Centers forDisease Control and Prevention estimates that nearly 40 million Americanadults (about 20% of the adult population) are obese. The prevalence ofobesity in the United States increased from 12% in 1991 to 19.8% in2000. The situation is similar in European countries, where 10-20% ofthe men and 10-25% of the women are obese. “Clinically severe obesity,”defined, as being 100 or more pounds overweight, is associated with anumber of serious and life-threatening health problems includingdiabetes, heart disease, respiratory problems, hypertension,gastroesophageal reflux disease, stress urinary incontinence,infertility, osteoarthritis, and some cancers. Conservative treatment,such as dieting, exercise and lifestyle changes, typically fails, makingsurgery the only hope for these patients. The surgical procedures aredesigned to restrict the size of the stomach so that food intake islimited and/or bypass steps in the normal digestive process (such as byconnecting the stomach to a lower segment of the small intestine) sothat food is either poorly digested or is rapidly passed. The NationalInstitute of Health consensus conference in 1991 established widelyaccepted guidelines and indications for the surgical management ofsevere obesity (see Gastrointestinal Surgery for Severe Obesity:National Institutes of Health Consensus Development ConferenceStatement. Am J Clin Nutr 1992; 55: 615S-9S). Surgical methods currentlyin use are described below.

The relationship of gastric accommodation and satiety in obeseindividuals has been studied (see Independent Influences of Body Massand Gastric Volumes on Satiation in Humans. Gastroenterology 2004; 126:432-440). Increased body mass index has been associated with delayedsatiation. Overweight and obese subjects ingest more at maximumsatiation compared with normal weight individuals. Increased fastinggastric volume, however, was not associated with body mass index.Chemoreceptors and mechanoreceptors in the stomach wall signal satiationthrough vagal and splanchnic nerves. When the stomach is relaxed(increased volume at a constant pressure) within the physiologicalrange, it requires higher increases in gastric pressure to activatestretch/tension receptors and thus induce symptoms such as satiation.Data suggests that satiation signals that inhibit ingestion are reducedwith increased body mass and that is not due to increased capacity orthe stomach's relaxation response to feeding. It has also beendetermined that the fasting volume of the distal stomach is greater inobese than control subjects (see Is There a Role for GastricAccommodation and Satiety in Asymptomatic Obese People?. ObesityResearch 2001; 9(11): 655-661). Gastric distention with eatingcontributes to the feeling of fullness or satiation. The mechanism isunclear, but distending the stomach stimulates gastric stretchreceptors, which trigger vagal discharges that activate hypothalamicneurons and induce the feeling of satiety. Peptides like leptin,cholecystokinin, and glucagons-like peptide 1 have been shown to evokesatiety, thereby reducing food intake.

The Roux-en-Y gastric bypass is used for surgical treatment of morbidobesity. This involves the partitioning the upper stomach with asurgical stapler and creating a 15 cc intact pouch along the lessercurvature of the stomach. After bypassing a 100 cm section of the bowel,the small intestine is attached to the gastric pouch.

Vertical banded gastroplasty is a simpler operation that involves onlythe creation of a gastric pouch but does not require extensive surgeryof the small intestine. In this procedure, biomaterials that are suturedaround the lumen to control stoma size and prevent late stretching ofthe opening. Biomaterials that are currently used for this procedureinclude Bard Mesh (C. R. Bard, Inc., Cranston, R.I., USA) and PeriStrips(Biovascular, Inc., St. Paul, Minn., USA).

Another technology used in bariatric surgery is laparoscopic banding.Gastric bands are commonly used to facilitate a reduction in foodconsumption. The bands are placed around the upper part of the stomachto create a small gastric pouch that limits food consumption and createsan earlier feeling of fullness. Some bands are inflated with saline andconnected to an access port placed close to the skin that allows theband to be adjusted. Although the devices are intended to remain inplace permanently, the procedure is completely reversible and does notrequire transection or stapling of the stomach and re-routing of thegastrointestinal tract.

Gastric bands have been developed and are commercially available. Forexample, Lap-Band™ is an implant that is made from silicone (Inamed,Santa Barbara, Calif., USA; see also U.S. Pat. No. 5,074,868; U.S. Pat.No. 5,226,429; U.S. Pat. No. 5,449,368; U.S. Pat. No. 5,910,149). TheSAGB™ or Swedish Adjustable Gastric Band (Obtech Medical A G, Zug,Switzerland) is an inflatable device made of silicone reinforced with atextile.

Gastric pouches were developed by Wilkinson (see U.S. Pat. No.4,403,604; U.S. Pat. No. 5,246,456). Gastric reservoir reduction wasaccomplished by wrapping the stomach with an inert fabric. The purportedadvantages of the gastric pouch include maintenance of restricted size,early satiety with eating, and passage of food through the wholeintestine. Gastric wrapping has been shown to create excess body massindex loss of 49, 66, 73, and 66 percent at 6, 12, 24 and 60 monthsrespectively (see A Comparison of the Gastric Bypass and the GastricWrap for Morbid Obesity. Surg. Gynecol. Obstet. 1993; 176: 262-266).

Electrical pacing has been applied with benefit in many areas ofsurgery. In the treatment of obesity, gastric myo-electric stimulationhas been shown to produce satiety. Gastric pacing has been shown tocreate excess body mass index loss of 18.8, 24.1, 22.3, and 32.6 percentat 6, 12, 24 and 60 months respectively (see Gastric Pacing as Therapyfor Morbid Obesity: Preliminary Results. Obesity Surgery 2002; 12:12S-16S). Each of the implants and procedures presently in use has oneor more deficiencies. For example, their construction can result incharacteristics that increase the risk of leakage, acute gastricdilatation, wound infection/seroma, obstruction, stomanarrowing/stenosis (with persistent vomiting), ulcer, band slippage orerosion, reservoir deflation/leak, anaemia, calciumdeficiency/osteoporosis, and vitamin and mineral deficiencies.Additional disadvantages include the presence of a foreign body,possible difficulties with reversibility if needed, and the increasedoperative time required to complete the more difficult procedures. Theprocedures described above can also result in extended patient stay inthe hospital due to the invasive nature of the procedures. Also, thereis a 19% risk of incisional hernia post-operatively when the procedureis performed by open surgical techniques.

Accordingly, there remains a need for implants for treating obesepatients and methods of making those implants.

SUMMARY

According to the invention there is provided a gastric constrictiondevice for constricting the volume of a stomach, the device comprising amaterial for extending over at least part of the wall of a stomach toconstrict the volume of the stomach, the device being configured torestrict expansion of a first region of the stomach wall and tofacilitate expansion of a second region of the stomach wall.

In one embodiment the constricting properties of the device vary over atleast part of the device. The material may be configured to extendpartially around a stomach to restrict expansion of the first region ofthe stomach wall over which the material extends, and to facilitateexpansion of the second region of the stomach wall which remainsuncovered by the material. The material may be configured to extendsubstantially circumferentially partially around a stomach.

In one case the material comprises a sheet. The sheet may besubstantially planar.

In one embodiment the sheet is configured to extend over only part ofthe wall of a stomach.

In another embodiment the sheet is configured to extend oversubstantially the entire wall of a stomach to enclose the stomach.

The constricting properties of the sheet may vary over the area of thesheet.

The device may comprise a fixation arrangement for fixing the sheet inposition extending over at least part of the wall of a stomach. In onecase a first region of the sheet is configured to be fixed to a secondregion of the sheet to fix the sheet in position extending over at leastpart of the wall of a stomach. The fixing arrangement may comprise atleast one band for extending from a first region of the sheet partiallyaround a stomach to a second region of the sheet. The band may bereleasably fixed to the second region of the sheet. In one case thefixation of the band to the second region of the sheet is adjustable.

In one embodiment the device comprises a first opening to accommodate anoesophagus and a second opening to accommodate a pylorus. The sheet maybe substantially shell-shaped.

According to another aspect, the invention provides a gastricconstriction device for constricting the volume of a stomach, the devicecomprising a band for extending at least partially around a stomach in aspiral to constrict the volume of the stomach. The band may be a spiralband. The band may in one case be pre-formed as a spiral.

The band may be substantially elongated.

In one case at least one spiral turn at least partially overlaps anadjacent spiral turn.

The device may comprise a fixation arrangement for fixing the band inposition extending at least partially around a stomach. In one case afirst region of the band is configured to be fixed to a second region ofthe band to fix the band in position extending at least partially arounda stomach. The first region may be located at an end of the band, andthe second region may be located at an opposite end of the band. Thefirst region may be located at an end of the band, and the second regionmay be located intermediate the ends of the band.

The invention also provides in another aspect a gastric constrictiondevice for constricting the volume of a stomach, the device comprising abio-absorbable material for absorption of at least some of the materialinto the stomach wall over time.

The device may be configured for absorption of substantially all of thedevice into the stomach wall over time. The absorption properties of thematerial may vary over the material. The absorption properties in onecase vary through the depth of the material. In another case, theabsorption properties vary across the area of the material.

The material may be at least partially of a laminate construction. Inone case the material comprises a first layer and a second layer, thefirst layer having a higher absorption rate than the second layer. Thefirst layer may be located adjacent to the second layer. The secondlayer may be configured to be located closer to a stomach wall than thefirst layer.

In one embodiment the material is at least partially porous to promotetissue in-growth. The first layer may have a higher pore density thanthe second layer. The first layer may have a smaller pore size than thesecond layer. In one case at least some of the pores form at least apartial gradient.

The material may comprise an anti-adhesion filler filling at least someof the pores. The material may comprise an anti-adhesion coating alongat least part of the surface of the material.

In another case the material comprises a film.

The device may comprise a band for extending at least partially around astomach to constrict the volume of the stomach. In one case the band issubstantially elongated. In another case the band comprises a loop bandfor extending at least partially around a

stomach in a loop. The device may comprise a plurality of loop bands forextending at least partially around a stomach at a plurality of regionsalong the stomach. Each loop band may be disconnected from an adjacentloop band. At least one loop band may at least partially overlap anadjacent loop band.

In another embodiment the band is configured to be extended at leastpartially around a stomach in a spiral. The band may be a spiral band.The band may be pre-formed as a spiral.

At least one spiral turn may at least partially overlap an adjacentspiral turn.

In one case the device comprises a fixation arrangement for fixing theband in position extending at least partially around a stomach. A firstregion of the band may be configured to be fixed to a second region ofthe band to fix the band in position extending at least partially arounda stomach. In one case the first region is located at an end of theband, and the second region is located at an opposite end of the band.In another case the first region is located at an end of the band, andthe second region is located intermediate the ends of the band.

In a further embodiment the device comprises a sheet for extending overat least part of the wall of a stomach to constrict the volume of thestomach. The device may be configured to restrict expansion of a firstregion of a stomach wall and to facilitate expansion of a second regionof the stomach wall.

The constricting properties of the device may vary over at least part ofthe device.

In another embodiment the material is configured to extend partiallyaround a stomach to restrict expansion of the first region of thestomach wall over which the material extends, and to facilitateexpansion of the second region of the stomach wall which remainsuncovered by the material. The material may be configured to extendsubstantially circumferentially partially around a stomach.

In one case the constricting properties of the sheet vary over the areaof the sheet.

The sheet may be configured to extend over only part of the wall of astomach. The sheet may be configured to extend over substantially theentire wall of a stomach to enclose the stomach.

In one case device comprises a fixation arrangement for fixing the sheetin position extending over at least part of the wall of a stomach. Afirst region of the sheet may be configured to be fixed to a secondregion of the sheet to fix the sheet in position extending over at leastpart of the wall of a stomach. The fixing arrangement may comprise atleast one band for extending from a first region of the sheet partiallyaround a stomach to a second region of the sheet. The band may bereleasably fixed to the second region of the sheet. In one case thefixation of the band to the second region of the sheet is adjustable.

In another embodiment the device comprises a first opening toaccommodate an oesophagus and a second opening to accommodate a pylorus.

In one case the sheet is substantially shell—shaped.

The device may comprise a gastric nerve stimulator.

In a further aspect, the invention provides a gastric constrictiondevice for constricting the volume of a stomach, the device comprising amaterial for extending over at least part of the wall of a stomach toconstrict the volume of the stomach, wherein the device comprises agastric stimulator. The gastric stimulator may comprise a gastric nervestimulator.

The invention also provides in a further aspect a gastric constrictiondevice for constricting the volume of a stomach, the device comprising asheet for extending over at least part of the wall of a stomach toconstrict the volume of the stomach, and a band for extending at leastpartially around the stomach to constrict the volume of the stomach.

The band may be configured to be located between the sheet and the wallof a stomach.

According to another aspect, the invention provides a gastricconstriction apparatus comprising:

-   -   a gastric constriction device of the invention; and    -   a collapsing device at least partially insertable into the        interior of a stomach to at least partially collapse the stomach        from a normal volume to a reduced volume.

The collapsing device may comprise a suction device to at leastpartially collapse a stomach by applying suction to the interior of thestomach.

In one case the collapsing device comprises a sealing member for sealingthe entry to a stomach at the oesophagus. The collapsing device maycomprise a sealing member for sealing the exit from a stomach at thepylorus. The sealing member may be inflatable.

The invention also provides in a further aspect a method of constrictingthe volume of a stomach, the method comprising the steps of:

-   -   applying a collapsing force to the stomach to at least partially        collapse the stomach from a normal volume to a reduced volume;    -   positioning a gastric constriction device relative to the        stomach; and    -   releasing the collapsing force;    -   the gastric constriction device then applying a constricting        force to the stomach to constrict the volume of the stomach.

The method may comprise the step of inserting a collapsing device atleast partially into the interior of the stomach before applying thecollapsing force. The collapsing force may be applied by applyingsuction to the interior of the stomach. In one case the method comprisesthe steps of sealing the entry to the stomach at the oesophagus beforeapplying suction. The method may comprise the step of sealing the exitfrom the stomach at the pylorus before applying suction. In one case thesealing is effected by inflating a sealing member. The collapsing forcemay be released by releasing suction of the interior of the stomach.

In one embodiment the gastric constriction device is positionedextending at least partially around the stomach. The gastricconstriction device may be positioned extending at least partiallyaround the stomach in a loop. The gastric constriction device may bepositioned extending at least partially around the stomach in a spiral.

In another embodiment the gastric constriction device is positionedextending over at least part of the wall of the stomach. The gastricconstriction device may be positioned extending over only part of thewall of the stomach.

The gastric constriction device may be positioned extending oversubstantially the entire wall of the stomach to enclose the stomach.

In a further embodiment a first part of the gastric constriction deviceis positioned extending at least partially around the stomach, and asecond part of the gastric constriction device is positioned extendingover at least part of the wall of the stomach. The first part may bepositioned between the second part and the wall of the stomach.

The method may comprise the step of fixing the gastric constrictiondevice in position relative to the stomach.

The method may comprise the step of adjusting the constricting forceapplied to the stomach.

In one case the gastric constriction device restricts expansion of afirst region of the stomach wall and facilitates expansion of a secondregion of the stomach wall.

In a further embodiment the method comprises the step of stimulatinggastric nerves.

The invention provides in another aspect a method of treating obesitycomprising the steps of:

-   -   constricting the volume of a stomach; and    -   stimulating gastric nerves

The step of constricting the volume of the stomach may comprise a methodof the invention.

The invention provides in one case a bariatric surgical method. Thepresent invention features a gastric harness implant that includes abiocompatible film. The film has a thickness of less than about 0.500inches for non-porous films and less than 1.000 inches for microporousfilms. A given implant can include more than one film (e.g., more thanone porous biocompatible film); for example, the invention features animplant that includes a first porous biocompatible film and a secondporous biocompatible film, the thickness of the implant being less thanabout 1.000 inches. The implants, including the materials from whichthey are made and the cell patterns they can contain are describedfurther below. It is not necessary to remove the gastric harness of theinvention. The gastric harness can be produced with biodegradablematerials that are resorbed by the body.

The implant is produced by processing a biocompatible polymer into afilm and forming pores in the film. In alternative embodiments, the filmcan be stretched or otherwise manipulated (e.g., trimmed, shaped, washedor otherwise treated) before or after forming pores in the film. Wherethe implant contains more than one film, the methods of the inventioncan be carried out by extruding a first biocompatible polymer to form afirst film, extruding a second biocompatible polymer to form a secondfilm, attaching the first film to the second film to produce a implant,and forming pores in the implant. Alternatively, the pores can be formedbefore the two films are adhered to one another. In that instance, themethod of making the implant can be carried out by: extruding a firstbiocompatible polymer to form a first film; forming pores in the firstfilm; extruding a second biocompatible polymer to form a second film;forming pores in the second film; and attaching the first film to thesecond film to produce a gastric harness implant.

Where the implant contains more than one film, the methods of theinvention can be carried out by extruding a first biocompatible polymerto form a first film, extruding a second biocompatible polymer to form asecond film, attaching the first film to the second film to produce aimplant, and forming pores in the implant. The pores can be formedbefore the two films are adhered to one another. The pores can havedifferent dimensions, the films can have different thicknesses, and thefilms can have different compositions all of which vary the healing andbiodegradation characteristics. In that instance, the method of makingthe implant can be carried out by: extruding a first biocompatiblepolymer to form a first film; forming pores in the first film; extrudinga second biocompatible polymer to form a second film; forming pores inthe second film; and attaching the first film to the second film toproduce a gastric harness implant. The gastric harness implant can bedesigned with controlled tissue ingrowth and remodelling to permanentlyalter the tissue and mechanical properties of the stomach.

Where a film is obtained, rather than made, the methods of making theimplant can simply require providing a given film that is then attached(e.g., reversibly or irreversibly bound by mechanical or chemicalforces), if desired, to another film and/or processed to include one ormore pores of a given size and arrangement. The single provided film (oradherent multiple films) can then be subjected to a process (e.g., laserablation, die punching, or the like) that forms pores within thefilm(s). Accordingly, any of the methods of the invention can be carriedout by providing a given biocompatible film, rather than by producing itby an extrusion or extrusion-like process.

The films can also be produced using casting, injection moulding or dipcoating techniques.

Preferably, the gastric harness implants of the invention will include(or consist of) a film that has a low profile (or reduced wallthickness) and that is biocompatible. A biocompatible film is one thatcan, for example, reside next to biological tissue without harming thetissue to any appreciable extent. As noted above, the film(s) used inthe implants of the invention can have pores (e.g., open passages fromone surface of the film to another) that permit tissue ingrowth and/orcellular infiltration.

The implants of the present invention offer a combination of highporosity, high strength, and low material content, and they may have oneor more of the following advantages. They can include pores or porousstructures that stimulate fibrosis and reduce inflammation; they canreduce the risk of erosion and formation of adhesions with adjacenttissue (this is especially true with implants having a smooth surfaceand atraumatic (e.g., smooth, tapered, or rounded edges); they cansimulate the physical properties of the tissue being repaired orreplaced, which is expected to promote more complete healing andminimise patient discomfort; their surface areas can be reduced relativeto prior art devices (having a reduced amount of material may decreasethe likelihood of an immune or inflammatory response). Moreover,implants with a reduced profile can be produced and implanted in aminimally invasive fashion; as they are pliable, they can be placed orimplanted through smaller surgical incisions. The methods of theinvention may also produce implants with improved optical properties(e.g., implants through which the surgeon can visualise underlyingtissue). Practically, the micromachining techniques that can be used toproduce the implants of the present invention are efficient andreproducible. The implants described herein should provide enhancedbiocompatibility in a low profile configuration while maintaining therequisite strength for the intended purpose.

The biocompatible films described above can be used to construct gastricharness implants that are designed to engage the outer surface of thestomach to reduce tension when food is consumed. The implant can beconfigured to encircle the stomach to act as a gastric harness. Ideally,the implant is inserted laparoscopically using minimally invasivetechniques and instrumentation. The invention also features methods forproducing gastric harness implants. These methods can include the stepof applying a shape memory material, for example an alloy, such asnitinol, to the gastric harness implant to facilitate sizing,attachment, and implantation. The gastric harness implant can also befabricated from a shape memory polymer (mnemoScience GmbH, Aachen,Germany).

The overall shape of the implants can vary depending on the size of theindividual and the stomach to be restricted. The overall length, width,and shape of the implants of the present invention can be designed toimpart a certain volume to the restricted stomach. Once the volume limitof the stomach is reached, the shaped gastric harness implant preventsan increase in tension on the stomach wall with the associated volumeincrease. This volume limit is typically approximately 15 cc or higher.

Because the volume of the stomach is determined at the time of surgery,the need to adjust the gastric harness implant is reduced. In addition,the gastric harness implant is in contact with a large area of thestomach, which reduces the potential for implant slippage. In oneembodiment of the invention, the gastric harness implant consists ofseparate panels that are positioned individually to restrict thestomach. In another embodiment, the gastric harness implant consists ofa strip of biocompatible material that is wrapped continuously aroundthe stomach. In another embodiment, the gastric harness implant can beused in conjunction with a gastric banding device to restrict the sizeof the gastric pouch that is formed with the band. In addition, thegastric harness implant will reduce the size of the access incision witha laparoscopic or minimally invasive approach to help reduceperipoperative morbidity and to speed recovery. The improvements willcome without creating a procedure that is too complex.

A further embodiment of the invention is to produce the gastric harnessimplant with variable elasticity such that certain areas of the implantexpand more under pressure or load. In this instance, a feeling ofsatiety may be created by placing the more elastic zones adjacent tonerves that are responsible for signalling with increases in gastricpressure to activate stretch/tension receptors and thus induce symptomssuch as satiation. The gastric implant may also be designed to wrap thestomach in select areas where the nerves responsible for signalling arenot present. Therefore, the stomach would be constrained in certainareas that are not responsible for signalling. An early feeling ofsatiety would be realised due to preferential expansion and creation ofstomach wall tension in the areas where the gastric harness is notpresent. Vagal nerves would be activated more readily creating a feelingof satiety.

A further embodiment of the invention is to produce the gastric implantfrom a bioresorbable or biodegradable material. The bioresorbable orbiodegradable implant will stay in position and restrict the stomachvolume over a predetermined time. The mechanical strength and shape ofthe gastric implant will restrict the stomach for the predeterminedtime. The gastric harness implant will create weight loss for thepatient over the predetermined time period. After the predetermined timethe gastric harness implant will be absorbed, and the implant will nolonger be a risk for chronic wound complications. In this case a secondprocedure to remove the implant will not be required.

This invention provides an implant device comprising a biocompatiblematerial that is configured to provide a gastric harness to constrainthe volume of the stomach. The harness may be configured to conformgenerally to a patient's stomach. The harness may extend from theoesophagus to the small intestine.

In one embodiment the harness defines an internal volume between anupper end and a lower end, which conforms generally to the externalgeometry of the stomach to constrain circumferential expansion of thestomach beyond a maximum adjusted volume during eating/digestion.

The gastric harness can be used in conjunction with laparoscopic bands.In one embodiment the harness defines an internal volume between anupper end of the stomach and a gastric band, which conforms generally tothe external geometry of the stomach pouch to constrain circumferentialexpansion of the stomach pouch beyond a maximum adjusted volume duringeating/digestion.

In one embodiment the harness defines a means for accepting a gastricpacing device. The harness defines an internal volume between an upperend and a lower end, which conforms generally to the external geometryof the stomach to constrain circumferential expansion of the stomachbeyond a maximum adjusted volume during eating/digestion. In addition,the gastric pacing device creates a feeling of satiety in the patient.

The biocompatible material may comprise a biocompatible film, which canbe of laminate construction. The film may be non-porous or may bemicroporous.

In one embodiment the biocompatible material comprises polypropylene,polyethylene terephthalate, polytetrafluoroethylene,polyaryletherketone, nylon, fluorinated ethylene propylene,polybutester, or silicone.

In another embodiment the biocompatible material is biodegradable. Thebiocompatible material may be at least partially absorbable by the body.The biocompatible material may comprise an absorbable polymer orcopolymer such as polyglycolic acid (PGA), polylactic acid (PLA),polycaprolactone, or polyhydroxyalkanoate.

The porous biocompatible film may comprise a biological material such ascollagen.

The porous biocompatible film used to construct the implant may comprisean adhesion prevention material such as hyaluronic acid. The adhesionprevention material can either coat the porous film or fill the pores.The adhesion prevention material may degrade as surrounding tissue healsand minimises the risk of future adhesions.

In one embodiment the biocompatible material has a plurality of cells.The biocompatible material may have a plurality of cells and one or moreof the cells in the plurality of cells has a diameter, measured alongthe longest axis of the cell, of about 10 to about 10,000 microns. Thebiocompatible material may have a plurality of cells and one or more ofthe cells of the plurality are essentially square, rectangular,sinusoidal, or diamond-shaped. One or more of the cells of the pluralitymay be substantially the same shape as the cell shown in Mesh2E.

In one embodiment each of the cells in the plurality of cells has aplurality of undulating elements in the form of a repeating pattern. Theundulating elements may be in phase and the force-displacementcharacteristics may restrict stomach expansion. Typically the pluralityof cells has a diameter greater than 50 microns and the implant hasforce displacement characteristics that restrict tissue movement in acontrolled manner.

In one embodiment the thickness of the porous biocompatible film is lessthan about 0.014 inches, less than about 0.013 inches, less than about0.012 inches, less than about 0.011 inches, less than about 0.010inches, less than about 0.009 inches, less than about 0.008 inches, lessthan about 0.007 inches, less than about 0.006 inches, less than about0.005 inches, less than about 0.004 inches, less than about 0.003inches, less than about 0.002 inches or about 0.001 inch.

In one embodiment the thickness of the porous biocompatible film is lessthan about 0.500 inches. The porous biocompatible film can be formedfrom multiple porous films less than about 0.014 inches, less than about0.013 inches, less than about 0.012 inches, less than about 0.011inches, less than about 0.010 inches, less than about 0.009 inches, lessthan about 0.008 inches, less than about 0.007 inches, less than about0.006 inches, less than about 0.005 inches, less than about 0.004inches, less than about 0.003 inches, less than about 0.002 inches orabout 0.001 inch.

In one embodiment the restricted stomach volume is 10 cc or greater.

The harness may comprise attachment regions, which may be adapted toreceive sutures, staples or the like.

The harness may comprise a fastener such as sutures for fastening theharness in position in use.

In one embodiment the biocompatible material is in the form of a stripfor winding around a patient's stomach. The strip may have attachmentpoints. The strip may form a circular band at the top of the stomachnear the oesophagus and at the bottom near the pylorus. The circularbands prevent slippage and provide a smooth interface with the stomachto prevent erosion. The central portion of the strip is wrapped aroundthe stomach in a circular fashion and is spaced such that the stomachwill not distend through the spacings when food is ingested. The stripcan be preformed and set to have three-dimensional qualities tofacilitate sizing and placement around the stomach.

In one embodiment the biocompatible material is in the form ofindividual strips for placement around a patient's stomach. The stripsmay have attachment points. The strips may form circular bands from thetop of the stomach near the oesophagus to the bottom near the pylorus.The individual strips can be placed and spaced evenly in a manner thataccommodates different individual's anatomy. The circular bands providea smooth interface with the stomach to prevent erosion. The individualstrips are spaced such that the stomach will not distend through thespacings when food is ingested. The strips can be preformed and set tohave three-dimensional qualities to facilitate sizing and placementaround the stomach.

In another embodiment the implant further comprises a gastric band. Thegastric band is of the same material as that of the harness or may be ofa different material than that of the harness.

In one embodiment the harness has a support, which may be of a shapememory material such as a shape memory alloy material, for exampleNitinol.

In another aspect the invention provides a gastric harness implantdevice for treating obesity, the device comprising: a biocompatiblematerial configured to engage the (outer) surface of the stomach torelieve tension on the stomach.

In a further aspect the invention provides a biocompatible materialforming a gastric harness implant defining an (internal) volume betweenan upper end and a lower end; said gastric harness implant adapted to besecured to the stomach to snugly conform to the external geometry of thestomach and to constrain circumferential expansion of the stomach beyonda maximum adjusted volume during eating/digestion; an adjustmentmechanism; a fastening mechanism.

In another aspect the invention provides a gastric harness implantcomprising an implantable material positioned around the stomach torestrict the volume of the stomach.

The biocompatible material may be configured to generally conform to apatient's stomach, the biocompatible material being configured to extendcircumferentially around the stomach. The implantable material may bepositioned from the oesophagus to the small intestine.

In another aspect the invention provides a method for treating obesity,the method comprising: inserting a balloon into the stomach with apredetermined volume; providing a gastric reinforcement device shapedand configured to engage at least a portion of the patient's stomach andto reduce the volume potential of the stomach; and placing the gastricreinforcement device on the patient's stomach such that said deviceextends circumferentially around the patient's stomach. The method mayinclude the step of providing a securement means for the device toprevent slippage.

In another aspect the invention provides a method for treating obesity,the method comprising: inserting a gastric tube with or withoutperforations and with or without a lumen into the stomach with apredetermined volume; applying a vacuum source to the lumen of thegastric tube; providing a gastric reinforcement device shaped andconfigured to engage at least a portion of the patient's stomach and toreduce the volume potential of the stomach; and placing the gastricreinforcement device on the patient's stomach such that said deviceextends circumferentially around the patient's stomach. The method mayinclude the step of providing a securement means for the device toprevent slippage.

In one aspect the invention provides a method for treating obesity, themethod comprising; surgically accessing the stomach; inserting a ballooninto the stomach with a predetermined volume; reducing the size of saidstomach; placing a gastric support device on said stomach; securing saidgastric support device to said stomach having a reduced size/volume,wherein said gastric support device comprises a biocompatible materialconfigured to constrain expansion of the stomach; surgically closingaccess to said stomach while leaving said gastric support device inplace on said stomach. In a further aspect the invention provides amethod for producing a gastric harness

implant, the method comprising: extruding a biocompatible polymer into afilm; and forming a plurality of cells in the film; wherein the methodmay further comprise the optional step of cleaning the implant.

The invention also provides a method for producing a gastric harnessimplant, the method comprising: extruding a biocompatible polymer into afilm, stretching the film; forming pores in the film to produce a softtissue implant; wherein the method may further comprise the optionalstep of cleaning the implant.

The invention further provides a method for producing a gastric harnessimplant, the method comprising: extruding a first biocompatible polymerto form a first film; extruding a second biocompatible polymer to form asecond film; attaching the first film to the second film to produce animplant; forming pores in the implant; shaping the implant into aconfiguration that imparts a known volume to the stomach; attaching ashape memory element to the implant; wherein the method may furthercomprise the optional step of cleaning the implant.

In another aspect the invention provides a method for producing a softtissue implant, the method comprising: extruding a first biocompatiblepolymer to form a first film; forming pores or cell patterns in thefirst film; extruding a second biocompatible polymer to form a secondfilm; forming pores in the second film; attaching the first film to thesecond film to produce a soft tissue implant; wherein the method mayfurther comprise the optional step of cleaning the implant.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art gastric banding device;

FIG. 2 is a perspective view of a gastric constriction device accordingto the invention;

FIG. 3 is a perspective view of the device of FIG. 2 extending around astomach;

FIG. 4 is a perspective view of a collapsing device according to theinvention;

FIG. 5 is a perspective view of an unrestricted stomach;

FIGS. 6 to 8 are perspective views illustrating constricting the volumeof the stomach of FIG. 5 using the gastric constriction device of FIG. 2and the collapsing device of FIG. 4;

FIG. 9 is a view along line IX-IX in FIG. 7;

FIG. 10 is a perspective view of another gastric constriction deviceaccording to the invention in a strip configuration restricting thestomach;

FIG. 11 is a perspective view of a further gastric constriction deviceaccording to the invention extending around a stomach;

FIG. 12 is a perspective view of a loop band of the device of FIG. 11 ina release configuration;

FIG. 13 is a perspective view of the loop band of FIG. 12 in a fixedconfiguration;

FIGS. 14 and 15 are perspective views similar to FIGS. 12 and 13 of aloop band of another gastric constriction device according to theinvention;

FIG. 16 is a plan view of an end of the loop band of FIG. 14;

FIG. 17 is a perspective view of a tool suitable for use with the loopband of FIGS. 14 to 16;

FIG. 18 is a perspective view similar to FIG. 12 of a loop band ofanother gastric constriction device according to the invention;

FIG. 19 is a plan view of an end of the loop band of FIG. 18;

FIG. 20 is a perspective view of another gastric constriction deviceaccording to the invention extending over the wall of a stomach torestrict the stomach;

FIG. 21 is a view along line XXI-XXI in FIG. 20;

FIGS. 22 and 23 are perspective views illustrating collapsing the volumeof a stomach using the gastric constriction device of FIG. 20 andanother collapsing device according to the invention;

FIG. 24 is a view along line XXIV-XXIV in FIG. 23;

FIGS. 25(a) and 25(b) are perspective views of a further gastricconstriction device according to the invention;

FIG. 26 is a perspective view of the device of FIG. 25 extending overthe wall of a stomach;

FIG. 27 is a plan view of another gastric constriction device accordingto the invention;

FIG. 28 is a perspective view of the device of FIG. 27 extending overthe wall of a stomach;

FIG. 29 is a perspective view of another gastric constriction deviceaccording to the invention;

FIGS. 30 and 31 are perspective views illustrating constricting thevolume of a stomach using a loop band according to the invention and thedevice of FIG. 29;

FIG. 32 is a view along line XXXII-XXXII in FIG. 31;

FIGS. 33 and 34 are perspective views of the gastric harness implant ofFIG. 29 used with a gastric banding device;

FIG. 35 is a view along line XXXV-XXXV in FIG. 34;

FIG. 36 is a plan view of another gastric constriction device accordingto the invention in a strip configuration with attachment points;

FIG. 37 is a perspective view of the device of FIG. 36;

FIG. 38 is a perspective view of a further gastric constriction deviceaccording to the invention extending around a stomach;

FIG. 39 is a perspective view of a material that can be machined toproduce a gastric constriction device according to the invention;

FIG. 40 is a perspective view of a laminated film structure showinglayers of biocompatible films bonded together;

FIGS. 41 and 42 relate to an implant designated Mesh2E, where FIG. 41 isa diagram of an exemplary pore, and FIG. 42 is a display of variousmeasured parameters within Mesh2E and the equations used to calculatethe surface area;

FIG. 43 is a diagram of an exemplary pore structure for Mesh2E;

FIG. 44 is a micrograph of Mesh2E;

FIG. 45 is a side view of a material of another gastric constrictiondevice according to the invention;

FIG. 46 is a side view of a first layer of the material of FIG. 45;

FIG. 47 is a plan view of the first layer of FIG. 46;

FIG. 48 is an enlarged, plan view of a part of the first layer of FIG.47;

FIGS. 49 to 51 are views similar to FIGS. 46 to 48 of a second layer ofthe material of FIG. 45;

FIGS. 52 and 53 are plan views of materials of further gastricconstriction devices according to the invention; and

FIG. 54 is a flow chart illustrating some of the steps in a method ofproducing a gastric constriction device according to the invention.

SELECTED REFERENCE NUMERALS IN DRAWINGS

-   10 gastric banding device-   12 biocompatible film-   14 laminated film structure-   16 cell pattern-   18 radius-   20 cell pattern structure-   22 machined film-   24 unrestricted stomach-   26 gastric harness implant-   28 attachment points-   32 strip configuration-   34 gastric band-   36 gastric pouch    Detailed Description

FIG. 1 illustrates a prior art gastric banding device 10 that can beused to perform gastric banding procedures.

Referring to FIG. 2 there is illustrated a gastric constriction device100 according to the invention. The device 100 comprises a substantiallyelongate spiral band 101 which may be extended around a stomach 24 in aspiral to constrict the volume of the stomach 24, as illustrated in FIG.3.

A fixation arrangement is provided at each end of the band 101. In thiscase, each fixation arrangement is provided in the form of an arrow-headshaped member 103 at the end of the band 101, which may be received inone of a plurality of corresponding slots 104 in the band 101. Asillustrated in FIG. 2, the slots 104 are located spaced a distance fromthe end of the band 101. The plurality of slots 104 enable a degree ofadjustment of the constriction force to be achieved.

It has been found that the spiral wrap of the band 101 may be positionedaround the blood vessels of the stomach wall in such an arrangement suchas to preserve blood flow.

FIG. 2 illustrates the gastric harness strip 101 in spiral wrap form.The strip material can be preformed with three-dimensional propertiesand may be made from a shape memory material. The strip 101 can alsoform bands at the top and bottom for securement near the oesophagus andpylorus. Slits 104 in the strip 101 can be used to create bands. Thecircular bands prevent slippage and provide a smooth interface with thestomach 24 to minimise the risk of erosion. The central portion iswrapped around the stomach 24 in circular fashion and is spaced suchthat the stomach 24 will not distend through the spacings when food isingested.

Multiple slits 104 in the strip 101 can be provided to adjust thediameter of the band. This permits a fit that prevents slippage whileminimising the risk of erosion if the band is placed too tightly aroundthe stomach 24. A tapered point 103 on the strip 101 facilitatesplacement through the slit 104. Holes 300 in the tapered point 103permit the use of instruments to facilitate grasping. The holes 300 alsopermit securement if a suture or a staple is used. The width of thetapered securement point 103 is wider than the slit 104 to create amechanical lock.

FIG. 4 illustrates a suction device 105 according to the inventionsuitable for use with the gastric constriction device 100 to constrictthe volume of the stomach 24. Together the suction device 105 and thegastric constriction device 100 provide a gastric constrictionapparatus.

The suction device 105 includes a plurality of openings 106 along thelength of the suction device 105 for applying suction to the interior ofthe stomach 24.

With reference to FIGS. 5 to 9, in use the suction device 105 isinserted through the oesophagus 107, into the interior of theunrestricted stomach 24, until the distal tip 108 of the suction device105 reaches the pylorus 109 (FIG. 6). The suction device 105 engages thetissue wall at the oesophagus 107 and at the pylorus 109 to effect aseal.

Suction is then applied to the interior of the stomach 24 using thesuction device 105. This suction exerts a collapsing force on thestomach 24, and causes the stomach 24 to partially collapse from thenormal volume (FIGS. 5 and 6) to a reduced volume (FIGS. 7 and 8). Atypical normal volume for the stomach is 750 cc, and a typical reducedvolume is 100 cc.

The spiral band 101 is positioned relative to the partially collapsedstomach 24 extending around the stomach 24 in a spiral, and the spiralband 101 is fixed in position by inserting each arrow-head shaped member103 into a corresponding slot 104 (FIG. 7).

The suction may then be released to release the collapsing force exertedon the stomach 24, and the suction device 105 is removed from thestomach 24 and oesophagus 107. The gastric constriction device 100remains fixed in position around the stomach 24 constricting the volumeof the stomach 24 (FIG. 8).

FIGS. 6 to 8 illustrate the gastric harness with calibrated vacuumassisted deployment. A fixed volume/diameter gastric tube 105 is placedinside the stomach 24 with or without perforations (illustrated withperforations). A means for applying a vacuum is also present.Perforations 106 are positioned inside the stomach 24 and a seal iscreated at the oesophagus 107 and pylorus 109. The gastric tube 105 mayhave fixed compliance and volume to replicate the pressure and volumerelationship experienced when food is ingested. The gastric harnessimplant 100 is placed around the stomach 24 with the gastric tube 105 inposition. Folds in the stomach wall are created as the surface area inthe outer wall is reduced. The gastric harness implant 100 remains inposition and the gastric tube 105 is removed (FIG. 8).

In FIG. 10 there is illustrated another gastric constriction device 110according to the invention, which is similar to the device 100 of FIG.2, and similar elements in FIG. 10 are assigned the same referencenumerals.

In this case the spiral band 101 extends around the stomach 24 in aspiral with each turn of the spiral partially overlapping an adjacentspiral turn.

FIG. 10 is a perspective view of a gastric harness implant 1 10 in astrip configuration 101 which in this case is wrapped around the stomach24. The implant 110 may extend from the oesophagus 107 beyond thepylorus 109 to the small intestine. The strip configuration 101 may bepassed around the stomach 24 and secured at the edges along attachmentpoints 28 with sutures or staples.

FIGS. 11 to 13 illustrate another gastric constriction device 120according to the invention, which is similar to the device 100 of FIG.2, and similar elements in FIGS. 11 to 13 are assigned the samereference numerals.

In this case the device 120 comprises a plurality of loop bands 121.Each band 121 is suitable for being extended around the stomach 24 in aloop. By extending the plurality of loop bands 121 around the stomach 24at a plurality of regions spaced along the stomach 24, the device 120constricts the volume of the stomach 24, as illustrated in FIG. 11.

FIGS. 11 to 13 illustrate the gastric harness implant formed fromindividual bands. The gastric harness 120 can be formed from individualbands 121 or strips of material. Each individual band 121 has anattachment point for variable adjustment. The strips 121 can be placedfrom the oesophagus 107 to the pylorus 109. The gastric bands 121provide a smooth interface with the stomach 24. The bands 121 are spacedsuch that the stomach 24 will not distend through the openings when foodis ingested. The individual gastric bands 121 have preformed curves andvariable adjustment means with spaced slits 104 to accommodate the taperpoint 103 (FIGS. 12 and 13).

Alternative fixing arrangements for fixing the loop bands 121 inposition extending around the stomach 24 are illustrated in FIGS. 14 to19.

The preformed individual bands 121 have two different attachment means.Each has a hole 300 for securement with a suture, staple, or otherattachment means. A tool 122 is illustrated for moving the tapered point103 through the slit 104 (FIGS. 14 to 16), and for moving the ratchetheadpiece 123 through the corresponding slot 104.

Referring to FIGS. 20 and 21 there is illustrated another gastricconstriction device 130 according to the invention, which is similar tothe device 100 of FIG. 2, and similar elements in FIGS. 20 and 21 areassigned the same reference numerals.

In this case the device 130 comprises a continuous sheet 131 forextending over the entire wall of the stomach 24. In this manner, thesheet 131 may enclose the stomach 24 and thereby constrict the volume ofthe stomach 24.

FIG. 20 is a perspective view of a gastric harness implant 26restricting the volume of the stomach 24. In another case the gastricharness implant 26 may extend from the oesophagus 107 beyond the pylorus109 to the small intestine. The implant 26 may be of a film materialsuch as those described below, for example the mesh 2E material.

In FIGS. 22 and 23, there is illustrated another suction device 140according to the invention, which is similar to the suction device 105of FIG. 4, and similar elements in FIGS. 22 and 23 are assigned the samereference numerals.

In this case the suction device 105 comprises a distal balloon member142 and a proximal balloon member 141. In use, the balloon members 141,142 are inflatable to engage the tissue wall to effect a seal prior tosuction being applied.

FIGS. 25 and 26 illustrate a further gastric constriction device 150according to the invention, which is similar to the device 130 of FIGS.20 and 21, and similar elements in FIGS. 25 and 26 are assigned the samereference numerals.

In this case, the sheet 131 is substantially shell-shaped, and extendsover only part of the wall of the stomach 24. Five bands 151 extend froma first side 152 of the sheet 131 partially around the stomach 24 to asecond side 153 of the sheet 131. In this manner, the bands 151 fix thesheet 131 in position extending over part of the wall of the stomach 24.

The bands 151 are releasably fixed to the second side 153 of the sheet131 by means of the arrow-head member 103 and corresponding slots 104arrangement.

FIGS. 25 and 26 illustrate the preformed gastric harness. The preformedgastric harness implant 150 is designed to engage the outer surface ofthe stomach 24 to reduce tension when food is ingested. The shape of theimplant 150 can be adjusted such that the lesser and lower curvatures ofthe stomach 24 can be preferentially reduced to accommodate less volumewhen food is ingested. The three dimensional properties can facilitatesizing and placement. The implant 150 is curved to adjust to the shapeof the stomach 24. Bands 151 are incorporated to wrap around the outersurface of the stomach 24. The spacing between bands 151 preventsstomach expansion when food is ingested. Slits 104 are placed in theimplant 150 to accept the bands 151 with a tapered point 103, whichpermits instrument manipulation and placement. The tapered point 103also has a hole 300 for accepting a suture, or staple for securing theimplant 150. The implant 150 is positioned and the bands 151 areadjusted using the slits 104 in the implant 150 to adjust the tension.In FIGS. 27 and 28, there is illustrated another gastric constrictiondevice 160 according to the invention, which is similar to the device150 of FIGS. 25 and 26, and similar elements in FIGS. 27 and 28 areassigned the same reference numerals.

In this case the lower two bands 151 extend from the first side 152 ofthe sheet 131 around the stomach 24 only partially towards the secondside 153. These lower two bands 151 are not fixed to the second side153. This arrangement results in an unconstricted portion of the stomach161. In this manner, the device 160 restricts expansion of the majorityof the stomach wall while facilitating expansion of this unconstrictedportion 161.

The unconstricted portion 161 is therefore free to expand or bulgeoutwardly upon ingestion. This expansion may trigger the feeling ofsatiation due to the presence of the vagal nerves in this portion 161 ofthe stomach 24.

FIGS. 27 and 28 illustrate the gastric harness implant to modulatestomach expansion. A preformed implant 160 is designed such that areasof the stomach 24 can preferentially expand more under pressure whenfood is ingested. Placing the more elastic zones adjacent to the nervesthat are responsible for signalling when stretch/tension receptors areactivated may create the feeling of satiety. Preferential expansion iscreated in the area where more elastic zones are present or where theimplant material is not present to constrain the stomach 24. Vagalnerves are more readily activated. An area for accepting a gastricpacing device may also be present. This may improve the efficacy of theconcept.

Referring to FIG. 29 there is illustrated another gastric constrictiondevice 170 according to the invention, which is similar to the device130 of FIGS. 20 and 21, and similar elements in FIG. 29 are assigned thesame reference numerals.

In this case, the sheet 131 extends around the full circumference of thestomach 24, but extends distally over only part of the wall of thestomach 24 from the oesophagus 107 approximately ⅓ to ⅔ of the distancetowards the pylorus 109.

In use, a laparoscopic band 171 is extended around the stomach 24 (FIG.30), and the device 170 is then extended around and along the stomach 24with the band 171 located between the sheet 131 and the stomach wall(FIGS. 31 and 32).

To fix the sheet 131 in position extending over the wall of the stomach24, a first region 172 of the sheet 131 is fixed directly to a secondregion 173 of the sheet 131.

FIGS. 29 to 32 illustrate the gastric harness implant used inconjunction with laparoscopic banding. The gastric harness 170 is usedto prevent expansion of the fixed volume pouch created duringlaparoscopic banding. The gastric harness 170 conforms generally to theoutside surface of the stomach 24 when the pouch is created. Holes 175are present for accepting sutures and/or staples. The gastric harness170 can be flared to minimise the risk of erosion and irritation. Thecross section (FIG. 32) demonstrates the interface between the stomachpouch and gastric harness 170.

As illustrated in FIGS. 33 to 35, the laparoscopic band 171 mayalternatively be extended around the sheet 131, after the sheet 131 hasbeen extended around and along the stomach 24. In this case, the sheet131 is located between the band 171 and the stomach wall.

The arrangement of FIGS. 29 to 32 is particularly advantageous. Thetechnique used to insert the band 171 in FIGS. 29 to 32 is a simple,easy to practise technique. In particular, this technique would becompatible with many alternative banding devices.

FIGS. 33 and 34 are perspective views of a gastric harness implant 170forming a gastric pouch 36. A gastric band 34 is provided. The band 34may be a part of the implant 170 or separate from it. The gastricharness implant 170 in this configuration prevents the gastric pouch 36from dilatation.

In FIGS. 36 and 37 there is illustrated another gastric constrictiondevice 180 according to the invention, which is similar to the device120 of FIG. 11, and similar elements in FIGS. 36 and 37 are assigned thesame reference numerals.

FIGS. 36 and 37 are perspective views of an implant material in a stripconfiguration 32 with attachment points 28.

FIGS. 36 and 37 illustrate the gastric harness strip with attachments. Astrip 121 is disclosed for winding around the stomach 24. The strip 121is intended to be placed laparoscopically using minimally invasivetechniques and instrumentation. The strip 121 has attachment points 28for accepting sutures, staples, or other securement means. Theattachment points 28 are rounded and are in the form of eyelets tominimise the risk of tissue reaction and erosion. Cell openings arepresent for tissue in-growth and fixation to the stomach wall.

In the embodiment of FIG. 38, a plurality of bands 190 are providedextending around the stomach 24 circumferentially and longitudinallyalong the stomach 24 for constricting the volume of the stomach 24.

FIG. 39 is a perspective view of a material that can be used to producea gastric constriction device of the present invention. The material maybe machined to produce a nonwoven gastric harness implant. The materialillustrated in FIG. 39 is a perspective view of a nonwoven biocompatiblefilm 12. The film 12 has known or discernible dimensions (width, length,and thickness), which can be modified or left intact in the manufactureof a gastric harness implant. In this case the film 12 is asingle-layer, smooth-edged film.

As shown in FIG. 40, the film 12 can be laminated to produce a film 14,which can also be used, with or without further modification, tomanufacture the implants of the present invention. Multiple layers ofbiocompatible film 12 can be added together to improve the mechanicalproperties (e.g., tear resistance and burst strength) of the implant.For example, a first film 12 can be bonded to a second film 12. Thebonding may be a thermal bond using hydraulic presses such as thosemanufactured by OEM Press Systems (Orange, Calif., USA).

Biocompatible materials useful in film 12 or film 14 can includenon-absorbable polymers such as polypropylene, polyethylene,polyethylene terephthalate, polytetrafluoroethylene,polyaryletherketone, nylon, fluorinated ethylene propylene,polybutester, and silicone, or copolymers thereof (e.g., a copolymer ofpolypropylene and polyethylene); absorbable polymers such aspolyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone, andpolyhydroxyalkanoate, or copolymers thereof (e.g., a copolymer of PGAand PLA); or tissue based materials (e.g., collagen or other biologicalmaterial or tissue obtained from the patient who is to receive theimplant or obtained from another person.) The polymers can be of theD-isoform, the L-isoform, or a mixture of both. An example of abiocompatible film 12 suitable for producing the laminated filmstructure 14 is expanded polytetrafluoroethylene.

In the case of a laminate 14, the various layers may be of the same ordifferent materials. For example, in the case of an absorbable material,the material of the layers may be selected to have varying rates ofabsorption.

FIGS. 41 and 42 relate to an implant designated Mesh2E. Referring to,FIG. 41, a sinusoidal cell pattern 16 has been designed with radius 18.The properties of the cell pattern 16 are described in detail in FIG.42.

FIG. 43 relates to a cell pattern structure 20 for cell pattern 16. Thecell pattern structure 20 has been constructed using computer-aideddesign.

FIG. 44 is a micrograph of a machined film 22. The machined film 22 isin this case constructed using a die-punching tool machined to cellpattern structure 20. The machined film 22 has porosity, which canimpart and support tissue ingrowth on high strength thin filmsubstrates. A radius 18 may be applied to each cell pattern 16 corner toimprove tear strength. Manufacturing methods to impart cell pattern 16include, but are not limited to, laser machining, die punching, waterjet cutting, and chemical etching. The lasers preferred for creatingsmooth edges on plastic films include, but are not limited to, CO₂,diode ultraviolet, or excimer lasers. An implant having cell pattern 16is expected to confer benefit to a patient in which it is implantedbecause of the substantially smooth edges of cell pattern 16. Openingsbetween 10 and 10,000 microns can be created in the film 22 with thegeometry cell pattern 16. An opening of about 2000 microns creates animplant with adequate porosity for tissue ingrowth and good mechanicalproperties.

In FIGS. 45 to 51 there is illustrated a bio-absorbable material 200suitable for use in forming the gastric constriction device of theinvention. The bio-absorbable nature of the material 200 facilitatesabsorption of the device into the stomach wall over time.

As illustrated in FIG. 45, the material 200 has a laminate construction.Both the first layer 201 and the second layer 202 of the material 200are porous to promote tissue in-growth. The first layer 201 has a higherpore density and smaller pore size than the second layer 202 (FIGS. 48and 51). In this manner, the first layer 201 has a higher absorptionrate and permits faster tissue remodelling than the second layer 202.

In use, the second layer 202 is located closer to the wall of thestomach 24 than the first layer 201.

FIGS. 45 to 51 illustrate the three-dimensional gastric harnessscaffold. A scaffold 200 comprising layers 201, 202 of porous materialis assembled. One layer 202 may have larger cells/pores with widerand/or thicker struts with longer degradation times. One layer may becomposed of a material with a longer degradation time. The pores may beformed before the layers 201, 202 are attached to one another. The poresmay have different dimensions and compositions, which vary the healingand degradation characteristics. Tissue will grow from the outside inand remodel at a controlled rate, which may permanently alter the volumepotential of the stomach 24 due to the mechanical properties of thegastric wall after tissue has been deposited.

Referring to FIG. 52 there is illustrated another bio-absorbablematerial 210 suitable for use in forming the gastric constriction deviceof the invention.

In this case the material 210 comprises an anti-adhesion coating alongat least part of the surface of the material 210.

In FIG. 53 there is illustrated a further bio-absorbable material 220suitable for use in forming the gastric constriction device of theinvention.

In this case the material 220 comprises an anti-adhesion filler 221filling at least some of the pores.

FIGS. 52 and 53 illustrate the gastric harness with adhesion preventionmaterial. The adhesion prevention material fills the cells and/or coatsthe porous material used to construct the gastric harness implant. Theadhesion prevention material is absorbed at a controlled rate or stayson the material permanently to prevent unwanted adhesions between thegastric harness and internal organs.

FIG. 54 is a flow chart illustrating some of the steps in a method ofproducing a gastric harness implant of the invention.

In an alternative method, the steps of laminating the films together maybe repeated after the step of machining the film.

The implant can have enhanced physical properties along its peripheraledges to improve suture or staple retention strength. The strength ofmaterial along the peripheral edges may be higher to improve thephysical properties in this region so that sutures do not pull out andcause failure. The material content in these regions can be increased toimprove the physical properties. In addition, attachment points can becreated along the edge for receiving sutures, staples, or adhesives. Theattachment points can be used to attach separate panels to one anotherto create the gastric implant.

Polytetrafluoroethylene (PTFE) polymer has useful properties as animplant material. PTFE can be processed into a microporous form using anexpansion procedure. Bard Vascular Systems (Tempe, Ariz., USA)manufactures ePTFE. Expanded PTFE offers a combination of strength andflexibility together with extensive biocompatibility.

Medical implant applications for the soft tissue implant technologydescribed above may include but are not limited to gastric banding andstomach restriction procedures. The soft tissue implant may be producedin a variety of shapes and sizes for the particular indication. One mayselect a non-absorbable gastric implant for morbidly obese patients thatrequire permanent treatment and long-term durability and strength.Alternatively, one may select an absorbable soft tissue implant forpatients that require temporary treatment of obesity when one wants toavoid the potential complications associated with a permanent implant.

In addition, the soft tissue implant product design may be produced inthree-dimensional forms to facilitate sizing. An example is an implantwith a curvature to construct a substantially cylindrical shape. A threedimensional structure could be machined using a system incorporating athird axis for micromachining. Alternatively, a substantiallytwo-dimensional soft tissue implant could be thermoformed into athree-dimensional shape after machining.

EXAMPLES Example 1

A nonwoven soft tissue implant was constructed using a biaxiallyoriented polymer film. Expanded PTFE film measuring 0.024 inches inthickness was obtained from Bard Vascular Systems (Tempe, Ariz., USA).Expanded PTFE was machined into the design Mesh2E cell patterns using adie punch produced by Elite Tool & Die (Smithstown, Ireland).

Example 2

A nonwoven soft tissue implant was constructed using biaxially orientedpolymer films. Expanded PTFE film, part number 1TM22250, was obtainedfrom BHA Technologies (Slater, Mo., USA). Twelve sheets of the film wereplaced between two sheets of DuPont Kapton 200HN film (Circleville,Ohio, USA). The sheet assembly was brought to 350° C. at 400 PSI ofconstant pressure for 15 minutes under vacuum. The laminated assemblywas machined into the design Mesh2E cell patterns using a die punchproduced by Elite Tool & Die (Smithstown, Ireland).

Example 3

A nonabsorbable gastric wrap was created using silicone tubing. A 100 cmlength of tubing was perforated in 1 cm increments with a 2 mm punchingtool. The gastric wrap was implanted into a canine at Charles RiverLaboratories (Ballina, Co. Mayo, Ireland). The assembly was used to wrapthe stomach of a 22.8 kg canine. Interrupted Mersilk 1 sutures (Ethicon,Somerville, N.J., USA) were used to secure the gastric wrap in positionagainst the stomach. In addition, a Maxon 1 monofilament absorbablesuture (United States Surgical, Norwalk, Conn., USA) was used to supportthe wrap by running the suture through the wrap perforations along thelongitudinal axis of the stomach. The canine was fed an unrestrictedhigh calorie diet and sacrificed at 30 days. The weight of the animal atsacrifice was 21.6 kg. The gastric wrap had incorporated into thestomach wall with a moderate degree of adhesion formation andinflammation present.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.

1. A gastric constriction device for constricting the volume of astomach, the device comprising a material for extending over at leastpart of the wall of a stomach to constrict the volume of the stomach,the device being configured to restrict expansion of a first region ofthe stomach wall and to facilitate expansion of a second region of thestomach wall.
 2. A device as claimed in claim 1 wherein the constrictingproperties of the device vary over at least part of the device.
 3. Adevice as claimed in claim 1 wherein the material is configured toextend partially around a stomach to restrict expansion of the firstregion of the stomach wall over which the material extends, and tofacilitate expansion of the second region of the stomach wall whichremains uncovered by the material.
 4. A device as claimed in claim 3wherein the material is configured to extend substantiallycircumferentially partially around a stomach.
 5. A device as claimed inclaim 1 wherein the material comprises a sheet.
 6. A device as claimedin claim 5 wherein the sheet is substantially planar.
 7. A device asclaimed in claim 5 wherein the sheet is configured to extend over onlypart of the wall of a stomach.
 8. A device as claimed in claim 5 whereinthe sheet is configured to extend over substantially the entire wall ofa stomach to enclose the stomach.
 9. A device as claimed in claim 5wherein the constricting properties of the sheet vary over the area ofthe sheet.
 10. A device as claimed in claim 5 wherein the devicecomprises a fixation arrangement for fixing the sheet in positionextending over at least part of the wall of a stomach.
 11. A device asclaimed in claim 10 wherein a first region of the sheet is configured tobe fixed to a second region of the sheet to fix the sheet in positionextending over at least part of the wall of a stomach.
 12. A device asclaimed in claim 10 wherein the fixing arrangement comprises at leastone band for extending from a first region of the sheet partially arounda stomach to a second region of the sheet.
 13. A device as claimed inclaim 12 wherein the band is releasably fixed to the second region ofthe sheet.
 14. A device as claimed in claim 12 wherein the fixation ofthe band to the second region of the sheet is adjustable.
 15. A deviceas claimed in claim 1 wherein the device comprises a first opening toaccommodate an oesophagus and a second opening to accommodate a pylorus.16. A device as claimed in claim 5 wherein the sheet is substantiallyshell-shaped.
 17. A gastric constriction device for constricting thevolume of a stomach, the device comprising a band for extending at leastpartially around a stomach in a spiral to constrict the volume of thestomach.
 18. A device as claimed in claim 17 wherein the band is aspiral band.
 19. A device as claimed in claim 18 wherein the band ispre-formed as a spiral.
 20. A device as claimed in claim 17 wherein theband is substantially elongated.
 21. A device as claimed in claim 17wherein at least one spiral turn at least partially overlaps an adjacentspiral turn.
 22. A device as claimed in claim 17 wherein the devicecomprises a fixation arrangement for fixing the band in positionextending at least partially around a stomach.
 23. A device as claimedin claim 22 wherein a first region of the band is configured to be fixedto a second region of the band to fix the band in position extending atleast partially around a stomach.
 24. A device as claimed in claim 23wherein the first region is located at an end of the band, and thesecond region is located at an opposite end of the band.
 25. A device asclaimed in claim 23 wherein the first region is located at an end of theband, and the second region is located intermediate the ends of theband.
 26. A gastric constriction device for constricting the volume of astomach, the device comprising a bio-absorbable material for absorptionof at least some of the material into the stomach wall over time.
 27. Adevice as claimed in claim 26 wherein the device is configured forabsorption of substantially all of the device into the stomach wall overtime.
 28. A device as claimed in claim 26 wherein the absorptionproperties of the material vary over the material.
 29. A device asclaimed in claim 28 wherein the absorption properties vary through thedepth of the material.
 30. A device as claimed in claim 28 wherein theabsorption properties vary across the area of the material.
 31. A deviceas claimed in claim 26 wherein the material is at least partially of alaminate construction.
 32. A device as claimed in claim 31 wherein thematerial comprises a first layer and a second layer, the first layerhaving a higher absorption rate than the second layer.
 33. A device asclaimed in claim 32 wherein the first layer is located adjacent to thesecond layer.
 34. A device as claimed in claim 32 wherein the secondlayer is configured to be located closer to a stomach wall than thefirst layer.
 35. A device as claimed in claim 32 wherein the material isat least partially porous to promote tissue in-growth.
 36. A device asclaimed in claim 35 wherein the first layer has a higher pore densitythan the second layer.
 37. A device as claimed in claim 35 wherein thefirst layer has smaller pore size than the second layer.
 38. A device asclaimed in claim 35 wherein at least some of the pores form at least apartial gradient.
 39. A device as claimed in claim 35 wherein thematerial comprises an anti-adhesion filler filling at least some of thepores.
 40. A device as claimed in claim 26 wherein the materialcomprises an anti-adhesion coating along at least part of the surface ofthe material.
 41. A device as claimed in claim 26 wherein the materialcomprises a film.
 42. A device as claimed in claim 26 wherein the devicecomprises a band for extending at least partially around a stomach toconstrict the volume of the stomach.
 43. A device as claimed in claim 42wherein the band is substantially elongated.
 44. A device as claimed inclaim 42 wherein the band comprises a loop band for extending at leastpartially around a stomach in a loop.
 45. A device as claimed in claim44 wherein the device comprises a plurality of loop bands for extendingat least partially around a stomach at a plurality of regions along thestomach.
 46. A device as claimed in claim 45 wherein each loop band isdisconnected from an adjacent loop band.
 47. A device as claimed inclaim 45 wherein at least one loop band at least partially overlaps anadjacent loop band.
 48. A device as claimed in claim 42 wherein the bandis configured to be extended at least partially around a stomach in aspiral.
 49. A device as claimed in claim 48 wherein the band is a spiralband.
 50. A device as claimed in claim 49 wherein the band is pre-formedas a spiral.
 51. A device as claimed in claim 48 wherein at least onespiral turn at least partially overlaps an adjacent spiral turn.
 52. Adevice as claimed in claim 42 wherein the device comprises a fixationarrangement for fixing the band in position extending at least partiallyaround a stomach.
 53. A device as claimed in claim 52 wherein a firstregion of the band is configured to be fixed to a second region of theband to fix the band in position extending at least partially around astomach.
 54. A device as claimed in claim 53 wherein the first region islocated at an end of the band, and the second region is located at anopposite end of the band.
 55. A device as claimed in claim 53 whereinthe first region is located at an end of the band, and the second regionis located intermediate the ends of the band.
 56. A device as claimed inclaim 26 wherein the device comprises a sheet for extending over atleast part of the wall of a stomach to constrict the volume of thestomach.
 57. A device as claimed in claim 26 wherein the device isconfigured to restrict expansion of a first region of a stomach wall andto facilitate expansion of a second region of the stomach wall.
 58. Adevice as claimed in claim 57 wherein the constricting properties of thedevice vary over at least part of the device.
 59. A device as claimed inclaim 57 wherein the material is configured to extend partially around astomach to restrict expansion of the first region of the stomach wallover which the material extends, and to facilitate expansion of thesecond region of the stomach wall which remains uncovered by thematerial.
 60. A device as claimed in claim 59 wherein the material isconfigured to extend substantially circumferentially partially around astomach.
 61. A device as claimed in claim 56 wherein the constrictingproperties of the sheet vary over the area of the sheet.
 62. A device asclaimed in claim 56 wherein the sheet is configured to extend over onlypart of the wall of a stomach.
 63. A device as claimed in claim 56wherein the sheet is configured to extend over substantially the entirewall of a stomach to enclose the stomach.
 64. A device as claimed inclaim 56 wherein the device comprises a fixation arrangement for fixingthe sheet in position extending over at least part of the wall of astomach.
 65. A device as claimed in claim 64 wherein a first region ofthe sheet is configured to be fixed to a second region of the sheet tofix the sheet in position extending over at least part of the wall of astomach.
 66. A device as claimed in claim 64 wherein the fixingarrangement comprises at least one band for extending from a firstregion of the sheet partially around a stomach to a second region of thesheet.
 67. A device as claimed in claim 66 wherein the band isreleasably fixed to the second region of the sheet.
 68. A device asclaimed in claim 66 wherein the fixation of the band to the secondregion of the sheet is adjustable.
 69. A device as claimed in claim 56wherein the device comprises a first opening to accommodate anoesophagus and a second opening to accommodate a pylorus.
 70. A deviceas claimed in claim 56 wherein the sheet is substantially shell-shaped.71. A device as claimed in claim 26 wherein the device comprises agastric nerve stimulator.
 72. A gastric constriction device forconstricting the volume of a stomach, the device comprising a materialfor extending over at least part of the wall of a stomach to constrictthe volume of the stomach, wherein the device comprises a gastricstimulator.
 73. A device as claimed in claim 72 wherein the gastricstimulator comprises a gastric nerve stimulator.
 74. A gastricconstriction device for constricting the volume of a stomach, the devicecomprising a sheet for extending over at least part of the wall of astomach to constrict the volume of the stomach, and a band for extendingat least partially around the stomach to constrict the volume of thestomach.
 75. A device as claimed in claim 74 wherein the band isconfigured to be located between the sheet and the wall of a stomach.76. A gastric constriction apparatus comprising: a gastric constrictiondevice as claimed in claim 1; and a collapsing device at least partiallyinsertable into the interior of a stomach to at least partially collapsethe stomach from a normal volume to a reduced volume.
 77. An apparatusas claimed in claim 76 wherein the collapsing device comprises a suctiondevice to at least partially collapse a stomach by applying suction tothe interior of the stomach.
 78. An apparatus as claimed in claim 76wherein the collapsing device comprises a sealing member for sealing theentry to a stomach at the oesophagus.
 79. An apparatus as claimed claim76 wherein the collapsing device comprises a sealing member for sealingthe exit from a stomach at the pylorus.
 80. An apparatus as claimed inclaim 78 wherein the sealing member is inflatable.
 81. A method ofconstricting the volume of a stomach, the method comprising the stepsof: applying a collapsing force to the stomach to at least partiallycollapse the stomach from a normal volume to a reduced volume;positioning a gastric constriction device relative to the stomach; andreleasing the collapsing force; the gastric constriction device thenapplying a constricting force to the stomach to constrict the volume ofthe stomach.
 82. A method as claimed in claim 81 wherein the methodcomprises the step of inserting a collapsing device at least partiallyinto the interior of the stomach before applying the collapsing force.83. A method as claimed in claim 81 wherein the collapsing force isapplied by applying suction to the interior of the stomach.
 84. A methodas claimed in claim 83 wherein the method comprises the steps of sealingthe entry to the stomach at the oesophagus before applying suction. 85.A method as claimed in claim 83 wherein the method comprises the step ofsealing the exit from the stomach at the pylorus before applyingsuction.
 86. A method as claimed in claim 84 wherein the sealing iseffected by inflating a sealing member.
 87. A method as claimed in claim83 wherein the collapsing force is released by releasing suction of theinterior of the stomach.
 88. A method as claimed in claim 81 wherein thegastric constriction device is positioned extending at least partiallyaround the stomach.
 89. A method as claimed in claim 88 wherein thegastric constriction device is positioned extending at least partiallyaround the stomach in a loop.
 90. A method as claimed in claim 88wherein the gastric constriction device is positioned extending at leastpartially around the stomach in a spiral.
 91. A method as claimed inclaim 81 wherein the gastric constriction device is positioned extendingover at least part of the wall of the stomach.
 92. A method as claimedin claim 91 wherein the gastric constriction device is positionedextending over only part of the wall of the stomach.
 93. A method asclaimed in claim 91 wherein the gastric constriction device ispositioned extending over substantially the entire wall of the stomachto enclose the stomach.
 94. A method as claimed in claim 81 wherein afirst part of the gastric constriction device is positioned extending atleast partially around the stomach, and a second part of the gastricconstriction device is positioned extending over at least part of thewall of the stomach.
 95. A method as claimed in claim 94 wherein thefirst part is positioned between the second part and the wall of thestomach.
 96. A method as claimed in claim 81 wherein the methodcomprises the step of fixing the gastric constriction device in positionrelative to the stomach.
 97. A method as claimed in claim 81 wherein themethod comprises the step of adjusting the constricting force applied tothe stomach.
 98. A method as claimed in claim 81 wherein the gastricconstriction device restricts expansion of a first region of the stomachwall and facilitates expansion of a second region of the stomach wall.99. A method as claimed in claim 81 wherein the method comprises thestep of stimulating gastric nerves.
 100. A method of treating obesitycomprising the steps of: constricting the volume of a stomach; andstimulating gastric nerves
 101. A method as claimed in claim 100 whereinthe step of constricting the volume of the stomach comprises a method asclaimed in claim
 81. 102. A bariatric surgical method as claimed inclaim 100.